jdstokes
- 520
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y''-3y'+2y=\mathrm{e}^x +1
Find y.
Going through the normal procedure we get the complementary function
y = A\mathrm{e}^x + B\mathrm{e}^{2x}.
Using the trial function
y = Cx\mathrm{e}^x + D
(because of overlap with the complementary function)
leads to
-C\mathrm{e}^x + 2D = \mathrm{e}^x+1
Does this mean
C=-1,D=1/2??
If so, the general soln is y = A\mathrm{e}^x + B\mathrm{e}^{2x} -x\mathrm{e}^x + 1/2.
According to Mathematica, however, the solution should be of the form
y = A\mathrm{e}^x + B\mathrm{e}^{2x} + 1/2(1-2\mathrm{e}^x -2\mathrm{e}^xx).
Am I using the wrong trial function or what?
Thanks in advance.
James
Find y.
Going through the normal procedure we get the complementary function
y = A\mathrm{e}^x + B\mathrm{e}^{2x}.
Using the trial function
y = Cx\mathrm{e}^x + D
(because of overlap with the complementary function)
leads to
-C\mathrm{e}^x + 2D = \mathrm{e}^x+1
Does this mean
C=-1,D=1/2??
If so, the general soln is y = A\mathrm{e}^x + B\mathrm{e}^{2x} -x\mathrm{e}^x + 1/2.
According to Mathematica, however, the solution should be of the form
y = A\mathrm{e}^x + B\mathrm{e}^{2x} + 1/2(1-2\mathrm{e}^x -2\mathrm{e}^xx).
Am I using the wrong trial function or what?
Thanks in advance.
James